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Deep DOF and diffraction artifacts

To capture a really deep depth of field you use a smaller aperture, bigger-up number. …This should be basic exposure theory that you're already comfortable…with as well as an understanding that where you focus when you're trying to…shoot deep depth of field matters. We covered this earlier.…I want to talk to you now about how after a point closing your aperture down…might actually soften your image a little bit due to an optical phenomena…and called diffraction.…Basically it works like this. As you close the aperture down to a smaller hole,…when the light gets squeezed through that hole, it gets diffractive, knocked…around a little bit, and it ends up getting softened.…

It doesn't focus as sharply as it should.…Now, what we're about to demonstrate and show is a pretty finicky level of sharpness.…Sharpness is a very subjective thing.…Opticians typically refer to it as acceptable sharpness, meaning everyone has…a different idea of what's sharp and what's not.…Sharpness and how much it matters also depends on how you're outputting.…

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Author

Released

2/11/2011

Many of the creative options available to a photographer hinge on an in-depth understanding of lenses. In Foundations of Photography: Lenses, Ben Long shows how to choose lenses and take full advantage of their creative options. The course covers fundamental concepts that apply to any camera, such as focal length and camera position, and shows how to evaluate and shop for DSLR lenses. The second half of the course focuses on shooting techniques: controlling autofocus, working with different focal lengths, and managing distortion and flare. The course also examines various filters and contains tips on cleaning and maintaining lenses.